Investigation on Spreading of Viral Infection of Seed Tuber Potatoes and Determination of Infective Indicator in Freidan Region of Isfahan

Freidan region with more than 11000 ha cultivation area of potato is an important seed potato production region in Iran. Tubers produced in this region were used in other areas and each year need more than 25000 ton virus free potato tubers for planting. To determine the duration of potato tubers being left free from viruses and the rate of infection of commercial potato cultivars to potato virus Y (PVY), potato virus X (PVX), potato virus M (PVM), potato virus S (PVS) and potato leaf roll virus (PLRV), an experiment was conducted in a complete randomized block design with four treatments included cultivars (class SE: Agria, Marfona, Konkord and Cosima) in four replications in Rozveh experimental station in 2003-2004. The cultivars were pre-emerged in laboratory and tested by ELISA, and healthy tubers were planted. At harvest time the tubers from two central rows in each treatment were collected and kept at 10ºC. In the second year the tubers were planted as the previous year and at harvest time, 250 tuber samples of each cultivar were collected from two central rows and kept at 10 ºC and dark condition . After breaking dormancy, the tubers were planted in pots. When the plants reach to 10 cm high, leaf samples were collected and tested by ELISA against the viruses. The results showed that PVY is dominant virus in the region with the highest infection rates in Marfona, and lowest infection rate in Konkord. The highest and lowest infection rate, to PVS, PVM and PLRV were observed in Marfona and Konkord, respectively. Regarding to the results, PVY could be used as an index indicating the duration time of potato tubers being used in successive planting for producing seed tubers.